1. Technical Field
The present invention relates to a technology for analyzing image data so as to extract a feature quantity of an image.
2. Related Art
According to the progress of a digital technology such as a computer, an image has been handled as digitalized image data in recent years. If the image is expressed in a form of image data, the image can be captured to a computer so as to add various corrections or adjustments, and the image data can be outputted to a printer so as to be printed. Although such the image data can be generated using various application programs which work on a computer, various imaging apparatus for generating image data such as a scanner, a digital camera and the like are developed and supplied to a market.
Further, when image data is corrected, the image data is analyzed to extract a feature quantity of image, and corrected corresponding to the extracted feature quantity. For example, Japanese Patent Publication Nos. 5-63972A (JP-A-5-63972) and 9-233336A (JP-A-9-233336). Various values are used as the feature quantity of image and, for example, the minimum grayscale value, the maximum grayscale value, and the average value of grayscale values are used. Since the feature quantity of image can be obtained by analyzing image data, the value of a feature quantity to be obtained depends on a color space of the image data.
However, recently, in order to generate high-quality image data by sufficiently utilizing performances of various imaging apparatus for generating image data, there is a tendency for a specific color space being used for every apparatus, where the specific color space is set corresponding to the characteristic of each imaging apparatus. The feature quantity of image is obtained by analyzing image data. As a result, if the image data is described with a specific color space in each apparatus, the values of feature quantities to be obtained are different. So, there is a problem that the feature quantities cannot be utilized across various image data even if those are extracted.